Foam materials are a class of commercial and industrial chemical-based materials. Foams can be prepared by aerating a foam composition, which can be derived by diluting a concentrated precursor composition. Depending on their application, foams require certain physical properties. Foam stability is one example of these physical properties.
Generally, foam stability refers to the ability of a foam to be used over an extended period of time. Individual components of a foam composition contribute toward different physical and chemical properties of both pre-foam mixtures and the final foam compositions. For example, certain surfactants can provide low surface tension and increased foamability. Further, the use of particular solvents can promote surfactant solubility and increased life span of the foam concentrate.
Foam stability is particularly preferable and important in firefighting applications, including fire prevention and fire extinguishment. Firefighting foams can be used in many different ways. High-expansion foams can be used when enclosed spaces must be quickly filled. Low-expansion foams can be used on burning spills. Generally, firefighting foams can be utilized in numerous locations, including inside of buildings, outside of buildings, underground, and in ships or other marine-related fires.
Unfortunately, foam stability has been a problem in firefighting applications. Particularly, the liquid that makes up firefighting foam slowly drains away from the foam. When a large amount of this liquid has drained from the bubble, the foam becomes fragile and ineffective at vapor suppression.
Previously, foam life has been extended by increasing the viscosity of the foam solution. This has been done by adding polysaccharides that impart a higher thixotropic viscosity to the foam solutions than previously attained. Polysaccharides have the added benefit of making the foam resistant to polar solvents such as alcohols and ketones. However, there is a limit to the quantity of polysaccharide a foam concentrate can contain and remain fluid. There is a threshold level of polysaccharide that above which the foam will become a semisolid or gel. Above this threshold, traditional methods of mixing the foam concentrate fail. Therefore, the length of time the life of the foam is extended is limited by the amount of polysaccharide that can be added to a foam concentrate.
Therefore, it is an object of the present invention to provide a firefighting extinguishing composition that increases the amount of polysaccharide that can be added to the foam concentrate, thereby extending the durability of firefighting foams and increasing the stability of the foam.